A new mandarin citrus tree hybrid Citrus reticulata is described. The new variety named xe2x80x98Yanovxe2x80x99 is desirable because of its lack of seeds and early ripening period between mid-November to December.
The present invention relates to a new and distinct variety of mandarin citrus tree Citrus reticulata hybrid developed by inventors Aliza Vardi, Pinchas Spiegel-Roy, Avraham Elchanati, Ahuva Frydman-Shani and Hana Neumann in Bet Dagan, Israel from a selection of plants grown from irradiated bud wood of the cultivar Nova.
Asexual reproduction by conventional bud grafting of the new variety at the Agriculture Research Organization Volcani Center in Bet Dagan, Israel, has shown that the new characteristics are stabilized and permanently fixed through successive propagation.
The objective in breeding the present new tree variety, known by the cultivar name xe2x80x98Yanovxe2x80x99, was to obtain a mid season ripening variety with few or no seeds. In the spring of 1987 and 1988 about 200 buds of the mandarin cultivar xe2x80x98Novaxe2x80x99 (unpatented) were irradiated at the Nahal Soreq Nuclear Center, Yavne, Israel, by exposure to 3.5 kh of gamma radiation from a Co60 source. Sour orange nucellar rootstocks were bud grafted with the individual buds of irradiated Nova bud wood and labeled mV1. Six to nine months after grafting the irradiated budwood, individual buds from the mV1 plants were re-grafted on Sour orange nucellar rootstocks to establish about 350 mV2 plants.
Field planting was established from container grown mV2 plants in the spring of 1989 and 1990. The first fruits were observed in January-March 1992 and a second observation made January-March of 1993 and 1994.
One of the selections, designated 1/22/20, had medium sized orange color fruit and was relatively easy to peel. The selection was distinguished from xe2x80x98Novaxe2x80x99 as having seedless fruit compared with 9-25 seeds for xe2x80x98Novaxe2x80x99 and having mainly sterile pollen. Typically 2% of the pollen grains of the selection were stained by acetocarmine compared with 95% for xe2x80x98Novaxe2x80x99.
Color designations have been determined from The R.H.S. Colour Chart published by The Royal Horticultural Society, London.
Table 1 shows some of the characteristics of the new tree compared to the parent xe2x80x98Novaxe2x80x99.
The following is a detailed description of the new mandarin citrus variety based on observations made under typical Israli grove conditions.
The tree shape and fruit appearance is similar to that of xe2x80x98Novaxe2x80x99. The tree has medium vigor. Very few thorns usually are present in the leafy part of branches, especially in the lower portion. Main branches have an upright attitude and young shoots have no anthocyanin coloration at the tip. The bearing of the tree is regular and the productivity is relatively high, about the same as for xe2x80x98Novaxe2x80x99. The canopy is moderately dense.
The leaves are similar to those of xe2x80x98Novaxe2x80x99. The leaf blade length is short to medium and the width is narrow to medium, the cross section is concave, the firmness is weak and the color is green. The petiole is narrow and very short to short.
The characteristics of the flowering and the flower parts are similar to those of xe2x80x98Novaxe2x80x99. Flowering for both occurs in end of March or in first half of April as measured in Bet Dagan, Israel. Both xe2x80x98Yanovxe2x80x99 and xe2x80x98Novaxe2x80x99 produce about the same number of flowers and flower drop for both occurs in April. Terminal flower buds have no anthocyanin coloration. Flowers are borne singly and have an average number of stamens (about 20) with complete style development. Anther color is pale yellow to white. Pollen fertility is very low as indicated by the observation that only 2% of the pollen grains were stained with acetocarmine in a test conducted at the Agricultural Research Organization, the Volcani Center, Israel, as compared with stainability of about 95% for Nova pollen grain.
All the flowers of mandarin cultivars are very much alike in color of petal (both sides are white), anther, pistil, etc.
The fruit is seedless even when optimal pollination conditions are employed. This compares with about 9-27 seeds per fruit in xe2x80x98Novaxe2x80x99 when optimal pollination conditions are employed. In other respects the fruit characteristics are in the range of the parent cv. xe2x80x98Novaxe2x80x99. The fruit shape is oblate and medium sized. When 50 fruits were measured, the fruit had an average weight 120 grams, an average height 58 mm, and an average diameter 65 mm. The fruit has a moderately depressed stalk end. The fruit surface is usually smooth with a yellow-orange color, 25A, on The Royal Horticultural Society of London Colour Chart, and bears an average number of conspicuous rind oil glands. Fruit ripening does not differ from outside of the canopy to the inside, but the fruit color of the outside canopy is a little brighter compared to the fruit color of the inside canopy. There is no persistence of the style and the areola is not completely developed. A navel is typically absent but sometimes present. The rind is thin and easy to peel.
The color of the albedo is white and the flesh is orange in color. The fruit contains 11-13 segments and is juicy. The external color of the seeds (when fresh) and dry is white. The internal seed coat is pale brown and the cotyledons are green. Polyembryonic seeds are present. The seed sizes, shape and texture are similar to that of the parent xe2x80x98Novaxe2x80x99mandarin. The fruit reaches maturity in mid-November to the end of December. The ripening of the fruit on the tree and within the fruit is uniform. If there is a heavy crop and the fruits are not picked before end of December it may becomes an alternate bearing (produces less fruit the following season). Pre-harvest drop of both developed and underdeveloped fruit is similar to that of the parent xe2x80x98Novaxe2x80x99 mandarin.